Mercedes *******

Took my wife's mercedes glc in for routine service at MB Bryanston. Vehicle still under service plan and warranty. Was called a short while later to be told, because i had changed the battery(to a highly reputable battery brand) to a non MB battery, they refused to do ANY work on the vehicle. What does a standard service ie change fluids etc have to do with a battery. I then asked them to please put in writing that they were refusing to service the vehicle due to the battery being changed. They also refused to do that, simply saying it was in the t&c's in the warranty booklet. I then phoned MBSA and spoke to a lady in the complaints dept, explained my predicament and asked for a letter, so i can give it to my attorneys. Will see what happens. I wonder whether the public really understands that MB will nullify your warranty and service plan if you don't replace any part of your vehicle with MB approved parts eg Windscreens/Tyres/ Batteries/ presumably wiper blades etc etc etc. I can possibly understand if the item that the owner replaced causes an issue, but in this case?? Simply ridiculous and all about MB forcing one to buy their overpriced parts. Strangely enough last year when the vehicle went in for its annual service, the service was done even though at that stage the battery had already been changed LOL.Guess the need to ******* Joe Public is more pressing now.As a previous buyer of 5 Mercedes vehicles, they have lost a future customer but seems like they really couldn't care.